No way anyone comes even close to Graf. Not Navratilova, nor Monica. If you just watched her play you would know. She was probably more dominant in tennis then Mike was in the NBA. Seles's athlecism does not even remotely match that of Graf's. As for Navratilova, she was good but the only competition she faced was Chris Everett.
There is, in my mind, some question as to whether Ali was even the greatest heavyweight boxer of all time, much less the greatest boxer of all time, much less the greatest athelete of all time. Let's remember Rocky Marciano who was the only undefeated heavyweight champion ever. But aside from the heavyweight division, two other boxers in my opinion should be considered. Sugar Ray Robinson and Chavez. Even if you argue that Ali was better than all three of these guys, let's call him the greatest boxer of all time. One of the top atheletes of the century though? Come on guys. I agree with popeye on all but these. Didrickson,Owens, Thorpe and maybe even Gretsky. Id also give it up for Laver if the competition wasn't so sparce in his day. No one else has ever won the grand slam in tennis (mens) much less done it twice. I'd even look at Carl Lewis before Ali or even Jackie Robinson. Get off the band wagon guys. DaDakota was right about Ali, although I prefer to judge him by his athleticism and not his character. No way is Ali a top 5 athelete of the century.